Skip to main content
SpringerLink
Log in

Effects of Roughness on the Performance of a threaded Zigzag Demister Using RSM and k − ω turbulent models

  • Published:
Sādhanā Aims and scope Submit manuscript

Abstract

In this paper, the effects of channel roughness on the droplet removal efficiency and pressure drop in a zigzag mist eliminator are investigated. The fluid flow, droplet dispersion and deposition through the demister are modelled using a commercial Computational Fluid Dynamics (CFD) tool. The turbulent airflow is simulated using two different Shear-stress Transport (SST) k-ω model and Reynolds Stress Model (RSM) with enhanced wall treatment. The Eddy Interaction Model (EIM) is also used to predict the trajectories of the droplets in the gas flow. The results show that inserting roughness increases the maximum velocity of the gas flow at the bends and enhances the removal efficiency with a little cost of an increase in the pressure drop for each bend. At the velocity inlet of 2 m/s with 6 μm droplets, the pressure drop and removal efficiency of the threaded zigzag demister with 5 threads increases by 22.7% and 16.08 %, respectively. Moreover, a higher value for the figure of merit is achieved for the threaded demister compared with the smooth unit which means that the effect of higher removal efficiency of the threaded unit is more pronounced than the effect of higher pressure drop showing the advantages of adding threads in demisters.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10

Similar content being viewed by others

Abbreviations

\( C_{D} \) :

Drag coefficient [-]

\( C_{L} \) :

Discrete phase model constant [-]

\( d \) :

Droplet diameter [μm]

\( D_{\omega } \) :

Cross-diffusion term [kg/m3s2]

\( F_{D} \) :

Coefficient in drag force calculation [1/s]

\( F_{x} \) :

Additional acceleration [m/s2]

\( g_{x} \) :

Gravitational acceleration [m/s2]

\( \tilde{G}_{k} \) :

Production of turbulence kinetic energy [kg/ms3]

\( G_{k} \) :

Production of turbulence kinetic energy [kg/ms3]

\( G_{\omega } \) :

Production of ω [kg/m3s2]

\( k \) :

Turbulence kinetic energy [m2/s2]

\( L_{e} \) :

Eddy length scale [m]

\( n \) :

Number of bends [-]

\( r \) :

Random number [-]

\( \text{Re}_{r} \) :

Relative Reynolds number [-]

\( \text{Re}_{ij} \) :

Reynolds stress tensor [m2/s2]

\( s \) :

Surface of sphere with same volume [m2]

\( S \) :

Actual surface of the droplet [m2]

\( S \) :

Width of the demister channel [mm]

\( S_{\varphi } \) :

Source term in transport equation

\( t_{cross} \) :

Droplet eddy crossing time [s]

\( T_{L} \) :

Integral time [s]

\( u^{\prime} \) :

Fluctuation of gas flow velocity [m/s]

\( \bar{u} \) :

Mean fluid phase velocity [m/s]

\( u \) :

Fluid phase velocity [m/s]

\( u_{p} \) :

Droplet velocity [m/s]

\( Y_{k} \) :

Dissipation of kinetic energy [kg/ms3]

\( Y_{\omega } \) :

Dissipation of ω [kg/m3s2]

\( \varGamma_{k} \) :

Effective diffusivity of kinetic energy [kg/ms]

\( \varGamma_{\omega } \) :

Effective diffusivity of \( \omega \) [kg/ms]

\( \varGamma_{\varphi } \) :

Diffusion coefficient in transport equation

\( \eta \) :

Droplet removal efficiency [%]

\( \eta_{B} \) :

Efficiency of each bend [%]

\( \alpha \) :

Bend angle [-]

\( \varepsilon \) :

Dissipation rate [m2/s3]

\( \lambda \) :

Bend wavelength [mm]

\( \mu_{t} \) :

Turbulent viscosity [kg/ms]

\( \mu \) :

Molecular viscosity of the fluid [kg/ms]

\( \rho_{p} \) :

Droplet density [kg/m3]

\( \rho \) :

Gas density [kg/m3]

\( \rho_{d} \) :

Droplet density [kg/m3]

\( \sigma_{k} \) :

Turbulent Prandtl number for k [-]

\( \sigma_{\omega } \) :

Turbulent Prandtl number for ω [-]

\( \tau \) :

Droplet relaxation time [s]

\( \nu \) :

Gas bulk velocity at inlet [m/s]

\( \omega \) :

Specific dissipation rate [1/s]

\( \phi \) :

Shape factor [-]

\( \varsigma \) :

Normally distributed random number [-]

\( \varphi \) :

General variable in transport equation

References

  1. Calvert S, Jashnani IL and Yung S 1974 Entrainment separators for scrubbers. J. Air Pollut. Control Assoc. 24: 971-975

    Article  Google Scholar 

  2. Chan JK-K and Golay M W Comparative evaluation of cooling tower drift eliminator performance. MIT Energy Laboratory: MIT Energy Laboratory, 1977

  3. Ushiki K, Nishzawa E, Beniko H and Iinoya K 1982 Performance of a droplet separator with multistage rows of flat blades. J. Chem. Eng. Jpn. 15: 292-298

    Article  Google Scholar 

  4. Phillips H and Deakin A Measurements of the collection efficiency of various demister devices. In: Proceedings of the Fourth Annual Meeting of the Aerosol Society, Loughborough, 1990

  5. Jøsang A I Numerical and Experimental Studies of Droplet-Gas Flow, Norwegian University of Science and Technology, 2002

  6. Bürkholz A 1989 Droplet separation: VCH Verlagsgesellschaft

  7. Gillandt I, Fritsching U and Riehle C 1996 Gas-particle flow in a comparison of measurements and simulations. FORSCH INGENIEURWES 62: 315

    Article  Google Scholar 

  8. Wang W and Davies G 1996 CFD studies of separation of mists from gases using vane-type separators. Chem. Eng. Res. Des. 74: 232-238

    Google Scholar 

  9. Wang Y and James P 1998 The calculation of wave-plate demister efficiencies using numerical simulation of the flow field and droplet motion. Chem. Eng. Res. Des. 76: 980-985

    Article  Google Scholar 

  10. Wang YI and James PW 1999 Assessment of an Eddy-Interaction Model and Its Refinements Using Predictions of Droplet Deposition in a Wave-Plate Demister. Chem. Eng. Res. Des. 77: 692-698

    Article  Google Scholar 

  11. Galletti C, Brunazzi E and Tognotti L 2008 A numerical model for gas flow and droplet motion in wave-plate mist eliminators with drainage channels. Chem. Eng. Sci. 63: 5639-5652

    Article  Google Scholar 

  12. Rafee R and Rahimzadeh H 2010 Performance Evaluation of a Curved Type Vane Separator at Different Plate Spacings in the Range of 25 to 35mm Using Numerical Simulation. Iran J. Chem. Chem. Eng. 29 (3)

  13. Rafee R, Rahimzadeh H and Ahmadi G 2010 Numerical simulations of airflow and droplet transport in a wave-plate mist eliminator. Chem. Eng. Res. Des. 88: 1393-1404

    Article  Google Scholar 

  14. McNulty K, Monat J and Hansen O 1987 Performance of commercial chevron mist eliminators. Chem. Eng. Prog. 83: 48-55

    Google Scholar 

  15. James P W, Wang Y, Azzopardi B J and Hughes J P 2003 The Role of Drainage Channels in the Performance of Wave-Plate Mist Eliminators. Chem. Eng. Res. Des. 81: 639-648

    Article  Google Scholar 

  16. Brunazzi E, Ghetti S, Merello C and Paglianti A 2004 Experimental study of the re-entrainment in wave-plate demisters. Proceedings of Convegno Gricu. 1:625-628

    Google Scholar 

  17. Estakhrsar M H H and Rafee R 2013 Effect of drainage channel dimensions on the performance of wave-plate mist eliminators. Korean J. Chem. Eng. 30: 1301-1311

    Article  Google Scholar 

  18. Hamedi Estakhrsar M H and Rafee R 2016 Effects of wavelength and number of bends on the performance of zigzag demisters with drainage channels. Appl. Math. Model. 40: 685-699

    Article  MathSciNet  Google Scholar 

  19. Lei G, Zhulin Y, Linjun Y and Zhongzhu G 2016 Numerical Study on the Penetration of Droplets in a Zigzag Demister. Environ. Eng. Sci. 33: 35-43

    Article  Google Scholar 

  20. Verlaan C C J Performance of novel mist eliminators 1991

  21. Houghton H and Radford W 1939 Measurements on eliminators and the development of a new type for use at high gas velocities. Trans. Am. Inst. Chem. Eng. 35: 427-433

    Google Scholar 

  22. Azzopardi J and Sanaullah K 2002 Re-entrainment in wave-plate mist eliminators. Chem. Eng. Sci. 57: 3557-3563

    Article  Google Scholar 

  23. Banitabaei S A, Rahimzadeh H and Rafee R 2012 Determination of minimum pressure drop at different plate spacings and air velocity in a wave-plate mist eliminator. Asia-Pacific J. Chem. Eng. 7: 590-597

    Article  Google Scholar 

  24. Xu Y, Yang Z and Zhang J 2017 Study on performance of wave-plate mist eliminator with porous foam layer as enhanced structure. Part II: Experiments. Chem. Eng. Sci. 171: 662-671

    Google Scholar 

  25. Xu Y, Yang Z and Zhang J 2017 Study on performance of wave-plate mist eliminator with porous foam layer as enhanced structure. Part I: Numerical simulation. Chem. Eng. Sci. 171: 650-661

    Article  Google Scholar 

  26. Hamedi Estakhrsar M and Rafee R 2013 Effect of drainage channel dimensions on the performance of wave-plate mist eliminators. Korean J. Chem. Eng. 1-11

  27. Zhang Z, Zhang W, Zhai Z J and Chen Q Y 2007 Evaluation of Various Turbulence Models in Predicting Airflow and Turbulence in Enclosed Environments by CFD: Part 2—Comparison with Experimental Data from Literature. HVAC&R Res. 13: 871-886

    Article  Google Scholar 

  28. Xiao H and Cinnella P 2019 Quantification of model uncertainty in RANS simulations: A review. Prog. Aerosp. Sci. 108: 1-31

    Article  Google Scholar 

  29. Menter FR 1994 Two-equation eddy-viscosity turbulence models for engineering applications. AIAA J. 32: 1598-1605

    Article  Google Scholar 

  30. Launder BE 1989 Second-moment closure: present… and future? Int. J. Heat Fluid Flow 10: 282-300

    Article  Google Scholar 

  31. Lien F-S and Leschziner M 1994 Assessment of turbulence-transport models including non-linear RNG eddy-viscosity formulation and second-moment closure for flow over a backward-facing step. Comput. Fluids 23: 983-1004

    Article  Google Scholar 

  32. Talebizadeh P, Rahimzadeh H, Babaie M, Javadi Anaghizi J, Ghomi HR, Ahmadi G, and Brown R 2015 Evaluation of residence time on nitrogen oxides removal in non-thermal plasma reactor. Plos One 10: e0140897

    Article  Google Scholar 

  33. Fluent A ANSYS Fluent 12.0 user’s guide. Ansys Inc. 2009; 15317:1-2498

  34. Maxey MR and Riley JJ 1983 Equation of motion for a small rigid sphere in a nonuniform flow. Phys. Fluids 26: 883-889

    Article  Google Scholar 

  35. Sardari P T, Rahimzadeh H, Ahmadi G and Giddings D 2018 Nano-particle deposition in the presence of electric field. J. Aerosol Sci. 126: 169-179

    Article  Google Scholar 

  36. Li A and Ahmadi G 1992 Dispersion and deposition of spherical particles from point sources in a turbulent channel flow. Aerosol Sci. Tech. 16: 209-226

    Article  Google Scholar 

  37. Talebizadehsardari P, Rahimzadeh H, Ahmadi G, Moghimi M A, Inthavong K and Esapour M 2019 Nano-particle deposition in axisymmetric annular pipes with thread. Part. Sci. Technol. 1-9

  38. Saffman P 1965 The lift on a small sphere in a slow shear flow. J. Fluid Mech. 22: 385-400

    Article  Google Scholar 

  39. Talebizadeh P, Rahimzadeh H, Ahmadi G, Brown R and Inthavong K 2016. Time history of diesel particle deposition in cylindrical dielectric barrier discharge reactors. J. Nanopart. Res. 18: 378

    Article  Google Scholar 

  40. Haider A and Levenspiel O 1989 Drag coefficient and terminal velocity of spherical and nonspherical particles. Powder Technol. 58: 63-70

    Article  Google Scholar 

  41. Tian L and Ahmadi G 2007 Particle deposition in turbulent duct flows—comparisons of different model predictions. J. Aerosol Sci. 38: 377-397

    Article  Google Scholar 

  42. Launder B E and Spalding D 1974 The numerical computation of turbulent flows. Comput. Methods Appl. Mech. Eng. 3: 269-289

    Article  Google Scholar 

  43. Zamora B and Kaiser A S 2011 Comparative efficiency evaluations of four types of cooling tower drift eliminator, by numerical investigation. Chem. Eng. Sci. 66: 1232-1245

    Article  Google Scholar 

  44. James P W, Azzopardi B J, Wang Y and Hughes J P 2005 A Model for Liquid Film Flow and Separation in a Wave-Plate Mist Eliminator. Chem. Eng. Res. Des. 83: 469-477

    Article  Google Scholar 

  45. Zhao J, Jin B and Zhong Z 2007 Study of the separation efficiency of a demister vane with response surface methodology. J. Hazard. Mater. 147: 363-369

    Article  Google Scholar 

  46. Wang Y I and James P W 1998 The Calculation of Wave-Plate Demister Efficiencies Using Numerical Simulation of the Flow Field and Droplet Motion. Chem. Eng. Res. Des. 76: 980-985

    Article  Google Scholar 

  47. Wang Y and James P 1999 Assessment of an eddy-interaction model and its refinements using predictions of droplet deposition in a wave-plate demister. Chem. Eng. Res. Des. 77:692-698

    Article  Google Scholar 

  48. Aftab S, Mohd Rafie A, Razak N and Ahmad K 2016 Turbulence model selection for low Reynolds number flows. PloS one. 11: e0153755

    Article  Google Scholar 

  49. Wang J, Kim S C and Pui D Y H 2008 Investigation of the figure of merit for filters with a single nanofiber layer on a substrate. J. Aerosol Sci. 39: 323-334

    Article  Google Scholar 

  50. Brown R C 1993 Air filtration: an integrated approach to the theory and applications of fibrous filters, Pergamon

Download references

Author information

Authors and Affiliations

  1. Department of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran

    Farhad Alamshahi & Hassan Rahimzadeh

  2. Faculty of Mechanical Engineering, Semnan University, Semnan, Iran

    Roohollah Rafee

  3. Institute of Research and Development, Duy Tan University, Da Nang, 550000, Vietnam

    M A Moghimi

  4. Faculty of Electrical – Electronic Engineering, Duy Tan University, Da Nang, 550000, Vietnam

    M A Moghimi

  5. Department of Engineering and Design, Staffordshire University, Stoke-On-Trent, ST4 2DE, UK

    M A Moghimi

  6. Metamaterials for Mechanical, Biomechanical and Multiphysical Applications Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam

    Pouyan Talebizadehsardari

  7. Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam

    Pouyan Talebizadehsardari

Authors
  1. Farhad Alamshahi
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Hassan Rahimzadeh
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Roohollah Rafee
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. M A Moghimi
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Pouyan Talebizadehsardari
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Pouyan Talebizadehsardari.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Alamshahi, F., Rahimzadeh, H., Rafee, R. et al. Effects of Roughness on the Performance of a threaded Zigzag Demister Using RSM and k − ω turbulent models. Sādhanā 45, 283 (2020). https://doi.org/10.1007/s12046-020-01510-2

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1007/s12046-020-01510-2

Keywords

Search

Navigation